GLENOLDEN, PA. - From Erie in the west to Scranton in the east, Pennsylvania is flecked with casualties the stubborn economic sluggishness and relentless globalization have inflicted on industrial communities. But in this middle-class Philadelphia suburb, Tom Danzi knows that the economy is denting even his business repairing damaged cars.

His Suburban Collision Specialists once had 27 employees kept busy by drivers stimulating the economy by producing fender benders. Now he has only 17. Many cash-strapped motorists keep driving cars with unrepaired scars. So, U.S. Senator Pat Toomey, a Republican seeking a second term, recently came here to commiserate and to warn that if his Democratic opponent wins she will make matters worse.

Which she probably will if she gets to the Senate. There Katie McGinty, a creature of the public sector who began her government-centric life giving Senator Al Gore environmental-policy tips, probably would be a reliable member of an unleashed, and perhaps unhinged, Democratic majority: As Toomey's seat goes, so, probably, goes the Senate.

If he loses, Republicans probably will lose control of the Senate, and that body probably will lose its character: Senate Democrats, who are situational ethicists regarding Senate rules, might further dilute the ability of the minority to require a 60-vote majority for, among many other things, confirmation of Supreme Court justices.

Toomey recited for a smattering of supporters here McGinty's policy enthusiasms, which encompass Democratic orthodoxy and have a cumulative price tag, he says, of $980 billion. While Toomey talked, on the sidewalk in front of Danzi's shop a small gaggle of McGinty supporters held signs to explain their prop, which needed an explanation: It was a large - the size of an ironing board - replica of the "friendship" bracelets children make at summer camps. This was the gaggle's labored way of saying that Toomey is Donald Trump's friend. Not exactly. Toomey supported Marco Rubio for the Republican nomination, then Ted Cruz, and has not yet said he will vote for Trump. But the fiction could be fatal where this election probably will be decided - here among moderate voters in the "collar" counties surrounding Philadelphia. Trump probably will carry some Pennsylvania counties with at least 75 percent, so Toomey must sail between the Scylla of endorsing Trump and thereby offending all non-Trumpkins, and the Charybdis of not endorsing and fueling the Trumpkins' constant rage.

In June, Toomey had a high single-digit lead. Today he is tied. He says that by November 8 more money will have been spent against him than against any other senator. And for him, some Republican good news is problematic: In Ohio, the weakness of Ted Strickland, the Democratic challenger to Senator Rob Portman, might cause Democrats to redirect money to McGinty. And some bad Republican news elsewhere is bad for Toomey: Because two Republican incumbent senators - Missouri's Roy Blunt and North Carolina's Richard Burr - are having more difficult races than anticipated, Toomey faces intensified competition for Republican funds.

Toomey surfed into office on the Republican wave of 2010, which was largely a result of a recoil against the Affordable Care Act. But even in that favorable environment he won by only 51-49 percent. He could, however, wind up owing two Senate terms to the ACA, which is unraveling in Pennsylvania, too: The Kaiser Family Foundation reports that by next year, only 28 counties will have three or more health insurers selling through the ACA exchanges, down from all 67 counties this year.

Toomey grew up in a union household in Rhode Island, earned a Harvard scholarship, did well on Wall Street, then joined his brothers in Allentown, Pa., to start what became a successful chain of restaurants. He successfully ran for Congress in 1998, and in 2004 did something eccentric: He kept his promise not to run for a fourth term. After losing a Senate contest that year, he became head of the free-market advocacy group Club for Growth. Today he is among the most important Republicans regarding the most important issue, tax reform, relating to the nation's most important challenge, the restoration of robust economic growth.

There is no really happy ending for Republicans in 2016. If Trump wins, the party's rupture with its past is complete and irreparable. If he loses narrowly, there will be an orgy of intramural recriminations, and the GOP's 2016-2019 will be like Spain's 1936-1939, an exceptionally uncivil civil war. If Trump loses emphatically, Democrats probably take the Senate. Unless Toomey wins this year's most consequential Senate race.